JP6935357B2 - Exhaust purification device - Google Patents

Description

The present invention relates to an exhaust gas purification device.

For example, a vehicle exhaust purification device equipped with a diesel engine (corresponding to an internal combustion engine) has a so-called DPF (Diesel Particulate Filter) that collects particulate matter in exhaust gas. In order to maintain the collection performance of the particulate matter of the DPF, it is necessary to periodically perform a so-called filter regeneration process to burn and incinerate the particulate matter in the collected DPF to remove it. In the filter regeneration process, unburned fuel is added to the oxidation catalyst provided on the upstream side of the DPF, and the unburned fuel is reacted in the oxidation catalyst to raise the temperature of the exhaust gas in the oxidation catalyst. There is a method in which exhaust gas heated to a temperature higher than the combustion temperature at which the particulate matter burns is allowed to flow into the DPF to burn and incinerate the particulate matter in the DPF.

However, the amount of unburned fuel added to raise the temperature of the exhaust gas in the oxidation catalyst to the above-mentioned combustion temperature or higher is the temperature of the exhaust gas flowing into the oxidation catalyst, the flow rate of the exhaust gas flowing into the oxidation catalyst, and the fuel. It fluctuates due to variations in properties. Conventionally, the temperature of the exhaust gas in the oxidation catalyst is set to the above regardless of the temperature of the exhaust gas flowing into the oxidation catalyst, the flow rate of the exhaust gas flowing into the oxidation catalyst, the variation in fuel properties, and the like. Since the amount of unburned fuel added that can exceed the combustion temperature is added, wasteful fuel is consumed.

In the exhaust gas purification device described in Patent Document 1, unburned fuel is added by post-injection in a diesel engine. The amount of unburned fuel added is obtained by multiplying the basic injection amount by the adjustment coefficient K, and the adjustment coefficient K is adjusted according to the DPF temperature estimated by the temperature of the exhaust gas. That is, by adjusting the adjustment coefficient K according to the temperature of the DPF, the amount of unburned fuel added is adjusted according to the temperature of the DPF, and a part of wasteful fuel consumption can be suppressed.

Japanese Unexamined Patent Publication No. 2008-23207

As described above, the amount of unburned fuel added to make the temperature of the exhaust gas in the oxidation catalyst equal to or higher than the above combustion temperature is the temperature of the exhaust gas flowing into the oxidation catalyst and the exhaust gas flowing into the oxidation catalyst. In the method described in Patent Document 1, the amount of unburned fuel added still contains wasteful fuel because it fluctuates depending on the flow rate, the variation in fuel properties, and the like. In recent years, further improvement in fuel efficiency has been desired, and it is desired to further reduce wasteful fuel consumption.

The present invention has been devised in view of these points, and more accurately determines the amount of unburned fuel added when the DPF filter regeneration process is performed, and further reduces wasteful fuel consumption. An object of the present invention is to provide an exhaust purification device capable of providing an exhaust gas purification device.

In order to solve the above problems, the first invention includes a filter that collects particulate matter contained in exhaust gas discharged from an internal combustion engine, and an oxidation catalyst arranged on the upstream side of the filter. In the exhaust gas purification device for purifying the exhaust gas, the inflow gas amount acquisition means for acquiring the inflow gas amount which is the inflow amount of the gas flowing into the oxidation catalyst and the inflow gas temperature which is the temperature of the gas flowing into the oxidation catalyst. The inflow gas temperature acquisition means for acquiring the above, the outflow gas temperature acquisition means for acquiring the outflow gas temperature which is the temperature of the gas flowing out from the oxidation catalyst, and the control means are provided, and the control means is located on the filter. When it is determined that a certain amount or more of the particulate matter has been collected, a filter regeneration treatment is performed by adding a fuel for filter regeneration to the oxidation catalyst to burn and incinerate the particulate matter in the filter, and the filter regeneration treatment is performed. Prior to obtaining the calorific value conversion coefficient indicating the relationship between the temperature rise temperature of the exhaust gas with respect to the amount of the filter regeneration fuel added to the oxidation catalyst, when obtaining the calorific value conversion coefficient, the fuel addition amount and the said The calorific value conversion coefficient is obtained based on the inflow gas amount, the inflow gas temperature, and the outflow gas temperature while the fuel of the fuel addition amount is being added to the oxidation catalyst, and is based on the calorific value conversion coefficient. This is an exhaust gas purification device that adjusts the filter regeneration fuel to be added to the oxidation catalyst during the filter regeneration process.

A second invention of the present invention is an exhaust gas purification device according to the first invention, wherein the control means obtains the calorific value conversion coefficient during idling operation or deceleration operation of the internal combustion engine. It is a purification device.

A third invention of the present invention is the exhaust gas purification device according to the first or second invention, wherein the control means generates heat after refueling the fuel in the internal combustion engine and based on the fuel after refueling. This is an exhaust gas purification device that uses a preset initial calorific value conversion coefficient as the calorific value conversion coefficient until the quantity conversion coefficient is obtained and updated only once after refueling.

A fourth invention of the present invention is an exhaust gas purification device according to any one of the first to third inventions, wherein the control means adds the fuel when obtaining the calorific value conversion coefficient. Based on the amount, the differential temperature integrated value obtained by integrating the difference between the exhaust gas temperature and the inflow gas temperature while the fuel of the fuel addition amount is being added to the oxidation catalyst, and the inflow gas amount. This is an exhaust gas purification device for obtaining the calorific value conversion coefficient.

A fifth invention of the present invention is an exhaust purification device according to any one of the first to fourth inventions, wherein the fuel for the oxidation catalyst is an exhaust passage on the upstream side of the oxidation catalyst. It is an exhaust gas purification device added by a fuel addition valve arranged in the above, or added by post injection by an injector in the cylinder of the internal combustion engine.

A sixth invention of the present invention is an exhaust gas purification device according to any one of the first to fifth inventions, and when the calorific value conversion coefficient is obtained, the operating state of the internal combustion engine is predetermined. In the exhaust gas purification device, the fuel for calculating the coefficient to be added to the oxidation catalyst is added in a preset fixed amount for a predetermined time so as to be completely consumed in the oxidation catalyst. be.

According to the first invention, the calorific value conversion coefficient is obtained, and the required fuel addition amount is made more accurate by adjusting the unburned fuel addition amount of the filter regeneration treatment based on the calorific value conversion coefficient. Can be asked for. Therefore, wasteful fuel consumption can be further suppressed.

According to the second invention, the calorific value conversion coefficient can be obtained more accurately by obtaining the calorific value conversion coefficient in an operating state where the fluctuation of the inflow gas temperature to the oxidation catalyst is small.

According to the third invention, even when the fuel properties are changed due to refueling of the fuel, the filter regeneration process in the DPF is performed with the optimum fuel addition amount in order to obtain the optimum calorific value conversion coefficient in the changed fuel properties. It can be carried out. Further, even when the filter regeneration process is started before the optimum calorific value conversion coefficient is obtained for the fuel properties after refueling, the filter regeneration process in the DPF can be appropriately performed by using the initial calorific value conversion coefficient.

According to the fourth invention, the influence of the temperature measurement error can be reduced by obtaining the difference temperature integrated value obtained by integrating the difference between the outflow gas temperature and the inflow gas temperature, and the calorific value conversion coefficient can be obtained more accurately. Can be sought.

According to the fifth invention, when fuel is added by the fuel addition valve, it can be added immediately before the oxidation catalyst. Also, when fuel is added by post-injection, the structure becomes simpler.

According to the sixth invention, since all the fuel is consumed in the oxidation catalyst, wasteful consumption can be suppressed and the calorific value conversion coefficient can be obtained more accurately.

It is a block diagram explaining the whole structure in the internal combustion engine to which the exhaust gas purification apparatus of 1st Embodiment is applied. It is a flowchart explaining the control process in the exhaust gas purification apparatus of 1st Embodiment. It is a block diagram explaining the whole structure in the internal combustion engine to which the exhaust gas purification apparatus of 2nd Embodiment is applied. It is a flowchart explaining the control process in 2nd Embodiment.

● [Explanation of the overall configuration and operation of the exhaust gas purification device 20 of the first embodiment (FIGS. 1 and 2)]
A first embodiment for carrying out the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram illustrating an overall configuration of an internal combustion engine 10 to which the exhaust gas purification device 20 of the first embodiment is applied. FIG. 2 is a flowchart illustrating a control process in the exhaust gas purification device 20 of the first embodiment.

● [Explanation of the overall configuration of the exhaust gas purification device 20 (Fig. 1)]
As shown in FIG. 1, the exhaust gas purification device 20 includes a control means 25, an inflow gas amount acquisition means 31, an oxidation catalyst 41, a filter 42, an inflow gas temperature acquisition means 50, and an outflow gas temperature acquisition means 52. , And a fuel addition valve 54. In the exhaust passage 12 of the internal combustion engine 10 (in this case, a diesel engine), an oxidation catalyst 41 and a filter 42 are sequentially provided as an exhaust purification device 20 from the upstream. The oxidation catalyst 41 is a catalyst that detoxifies hydrocarbons (HC) and carbon monoxide (CO), and the filter 42 is a so-called DPF (Diesel Particulate Filter) that collects particulate matter in the exhaust gas.

The internal combustion engine 10 is provided with an injector 56 for injecting fuel supplied from the fuel tank 22 into a cylinder, and is provided with a rotation detecting means 34 for detecting an operating state. The intake passage 11 is provided with an inflow gas amount acquisition means 31 for acquiring an inflow amount of gas (air) taken into the internal combustion engine 10. The fuel addition valve 54 is arranged on the upstream side of the oxidation catalyst 41 in the exhaust passage 12, and injects fuel into the exhaust passage 12 to add the fuel to the oxidation catalyst 41. The illustration of the fuel supply piping from the fuel tank 22 to the injector 56 and the fuel tank 22 to the fuel addition valve 54 is omitted for convenience of explanation.

The control means 25 includes a fuel gauge 24, an inflow gas amount acquisition means 31, an accelerator opening degree detection means 33, a rotation detection means 34, an inflow gas temperature acquisition means 50, an outflow gas temperature acquisition means 52, a fuel addition valve 54, an injector 56, and the like. Each of them is connected.

The control means 25 outputs a control signal to each of the fuel addition valve 54 and the injector 56 for control. The control means 25 adjusts the fuel supply amount by controlling the opening degree of the fuel addition valve 54, the energization time, and the like. Further, the control means 25 outputs a drive signal to the injector 56 that injects fuel into the internal combustion engine 10 to control the timing of injecting fuel into the cylinder and the amount of fuel to be injected.

The fuel gauge 24 is provided in the fuel tank 22 and outputs a signal corresponding to the detected amount of fuel in the fuel tank 22 to the control means 25. The inflow gas amount acquisition means 31 is, for example, an air flow sensor, which corresponds to the inflow amount [g / s] of the gas provided in the intake passage 11 and sucked into the internal combustion engine 10 (= the flow rate of the gas flowing into the oxidation catalyst 41). ) Is output to the control means 25.

The accelerator opening degree detecting means 33 outputs a detection signal corresponding to the opening degree of the accelerator operated by the driver (that is, the load requested by the driver) to the control means 25. The rotation detecting means 34 outputs, for example, a detection signal corresponding to the rotation of the crankshaft of the internal combustion engine 10 to the control means 25.

The inflow gas temperature acquisition means 50 is arranged on the upstream side of the oxidation catalyst 41 in the exhaust passage 12, and outputs a signal corresponding to the temperature of the gas flowing into the oxidation catalyst 41 to the control means 25. The outflow gas temperature acquisition means 52 is arranged on the downstream side of the oxidation catalyst 41 in the exhaust passage 12, and outputs a signal according to the temperature of the gas flowing out from the oxidation catalyst 41 to the control means 25.

The control means 25 determines the operating state (for example, idling operation, deceleration operation) of the internal combustion engine 10 based on the signals from each of the accelerator opening degree detecting means 33 and the rotation detecting means 34.

● [Explanation of filter playback processing]
The filter regeneration process is performed by the control means 25 adding an amount of filter regeneration fuel adjusted based on the calorific value conversion coefficient k to the oxidation catalyst 41 and burning and incinerating the particulate matter in the filter 42. The calorific value conversion coefficient k is the fuel addition amount [g / s] required to raise the unit gas flow rate (1 g / s) by 1 ° C.

The calorific value conversion coefficient k is the total fuel addition amount [g], the total flow rate of the gas flowing into the oxidation catalyst 41 (inflow gas amount) [g], and the calorific value due to the fuel flowing into the oxidation catalyst 41 (= oxidation catalyst). It is obtained based on the gas temperature at the time of outflow-gas temperature at the time of inflow of the oxidation catalyst) [° C]. The adjusted addition amount [g] of the fuel for filter regeneration is a calorific value conversion coefficient k [1 / ° C.] × (target outflow gas temperature of the oxidation catalyst 41 −inflow gas temperature of the oxidation catalyst 41) [° C.] ×. It is obtained based on (total amount of gas flowing into the oxidation catalyst 41) [g]. The target outflow gas temperature of the oxidation catalyst 41 is a temperature at which the particulate matter can be burned and incinerated in the filter 42, and is a temperature in the range of 600 ° C. to 650 ° C. Further, the calorific value conversion coefficient k may be obtained by multiplying the obtained calorific value conversion coefficient k by, for example, 1.1 in order to perform the filter regeneration processing more reliably.

● [Explanation of operation in the exhaust gas purification device 20 (Fig. 2)]
The control processing procedure of the control means 25 (see FIG. 1) in the exhaust gas purification device 20 will be described with reference to the flowchart of FIG. When the control means 25 is activated, the control means 25 executes the entire process at predetermined time intervals (for example, several [ms] intervals). Hereinafter, each step will be described in detail.

● [Explanation of overall processing]
In step S100, if the control means 25 determines that the fuel is refueled (Yes), the process proceeds to step S110, and if it is not determined that the fuel is refueled (No), the process proceeds to step S130. Based on the detection signal of the fuel gauge 24 (see FIG. 1), the control means 25 determines that the fuel is refueled, for example, when the measured amount of fuel increases as compared with the previously measured amount of fuel. judge.

In step S110, the control means 25 sets the calorific value conversion coefficient k to the initial calorific value conversion coefficient ki, and proceeds to step S120. As a result, the control means 25 sets the initial calorific value conversion coefficient ki as the calorific value conversion coefficient k until the calorific value conversion coefficient k is obtained and updated only once after refueling based on the fuel after refueling. Therefore, the control means 25 appropriately performs the filter regeneration process in the filter 42 (see FIG. 1) even when the filter regeneration process is started before the optimum calorific value conversion coefficient k is obtained and updated in the fuel properties after refueling. conduct. The initial calorific value conversion coefficient ki is a calorific value conversion coefficient that is preset and stored in the control means 25 in consideration of the deterioration over time of the oxidation catalyst 41 and the variation in fuel properties.

In step S120, the control means 25 sets the coefficient update flag = 0 and proceeds to step S130. The coefficient update flag is a flag indicating the update of the calorific value conversion coefficient k, and is set to 0 when it is determined that the fuel is refueled. In the state where the coefficient update flag = 0, heat is generated by the fuel after refueling. It is set to 1 when the quantity conversion coefficient k is obtained and updated. As a result, the acquisition of the calorific value conversion coefficient k after refueling is limited to one time.

In step S130, when the control means 25 determines that the filter 42 has collected a predetermined amount or more of the particulate matter (Yes), the process proceeds to step S140, and the filter 42 contains the predetermined amount or more of the particulate matter. If it is not determined that the particles have been collected (No), the process proceeds to step S150. The control means 25 may determine, for example, that a predetermined amount or more of particulate matter has been collected by the filter 42 based on the elapsed time from the time when the filter regeneration process was performed last time.

In step S140, the control means 25 performs a filter regeneration process and ends the entire process.

In step S150, when the control means 25 determines that the coefficient update flag = 0 (Yes), the process proceeds to step S200 (acquisition and update of the calorific value conversion coefficient), and when the coefficient update flag = 0 is not determined (Yes). No) ends the whole process.

● [Explanation of acquisition and update of calorific value conversion coefficient (step S200)]
Hereinafter, the processing procedure for acquiring and updating the calorific value conversion coefficient k in step S200 will be described. The control means 25 performs a process of initializing the fuel addition amount, the differential temperature integrated value, and the total inflow gas amount to 0 at the start of acquisition and update of the calorific value conversion coefficient.

In step S205, when the control means 25 determines that the inflow gas temperature is equal to or higher than the obtainable temperature of the calorific value conversion coefficient k (Yes), the process proceeds to step S210, and the inflow gas temperature can acquire the calorific value conversion coefficient. If it is not determined that the temperature is higher than the temperature (No), the process proceeds to step S265. The control means 25 determines the inflow gas temperature as a calorific value conversion coefficient by comparing it with a value stored in advance in the control means 25 based on the acquisition signal of the inflow gas temperature acquisition means 50 (see FIG. 1). Determine if the temperature is above the retrievable temperature. The obtainable temperature is a value corresponding to the material of the oxidation catalyst used for the oxidation catalyst 41, and is stored in the control means 25 in advance.

In step S210, when the control means 25 determines that the internal combustion engine 10 (see FIG. 1) is in idling operation (Yes), the process proceeds to step S215 and determines that the internal combustion engine 10 is in idling operation. If not (No), the process proceeds to step S220. The control means 25 determines whether or not the engine is idling based on the information from the accelerator opening degree detecting means 33 (see FIG. 1) and the rotation detecting means 34 (see FIG. 1).

In step S220, if the control means 25 determines that the internal combustion engine 10 is in deceleration operation (Yes), the process proceeds to step S215, and if the internal combustion engine 10 does not determine that it is in deceleration operation (No). Proceeds with the process in step S265. The control means 25 determines whether or not the vehicle is in deceleration operation based on the information from the accelerator opening degree detecting means 33 and the rotation detecting means 34.

In step S215, the control means 25 controls the fuel addition valve 54 (see FIG. 1) to add fuel (fuel for coefficient calculation) to the exhaust passage 12 of the fuel, and proceeds to the process in step S225. The coefficient calculation fuel is used in the oxidation catalyst 41 when the calorific value conversion coefficient k is obtained and the operating state of the internal combustion engine 10 is a predetermined operating state (idling operation, deceleration operation in the case of this embodiment). It is a fuel to be added. The control means 25 adds a predetermined fixed amount so that all the coefficient calculation fuel is consumed in the oxidation catalyst 41 for a predetermined time (in this case, the time from the start to the end of the addition). The fuel addition amount is the total amount of the coefficient calculation fuel added when the calorific value conversion coefficient k is obtained.

In step S225, the control means 25 acquires and stores the amount of inflow gas flowing into the oxidation catalyst 41 based on the information of the inflow gas amount acquisition means 31 (see FIG. 1), and proceeds to the process in step S230. The control means 25 integrates the acquired inflow gas amount to obtain the total inflow gas amount.

In step S230, the control means 25 acquires and stores the inflow gas temperature flowing into the oxidation catalyst 41 based on the information of the inflow gas temperature acquisition means 50 (see FIG. 1), and proceeds to the process in step S235.

In step S235, the control means 25 acquires and stores the outflow gas temperature flowing out from the oxidation catalyst 41 based on the information of the outflow gas temperature acquisition means 52 (see FIG. 1), and proceeds to the process in step S240.

In step S240, the control means 25 obtains and stores the difference temperature integrated value obtained by integrating the difference between the outflow gas temperature (step S235) and the inflow gas temperature (step S230) while the fuel is being added to the oxidation catalyst 41. , Step S245 proceeds with the process.

In step S245, when the control means 25 determines that the predetermined addition time has elapsed from the start of fuel addition (Yes), the process proceeds to step S250, and the predetermined addition time has elapsed from the start of fuel addition. If no determination is made, step S200 (acquisition and update of calorific value conversion coefficient) is terminated, and the process returns to the overall process. The predetermined addition time is, for example, about 10 s to 20 s.

In step S250, the control means 25 controls the fuel addition valve 54 to finish the addition of the fuel to the exhaust passage 12, and proceeds to the process in step S255.

In step S255, the control means 25 obtains the calorific value conversion coefficient k and proceeds to the process in step S260. The control means 25 obtains a calorific value conversion coefficient from the fuel addition amount, the inflow gas amount, the inflow gas temperature, and the outflow gas temperature from the start of the addition to the end of the addition. The control means 25 obtains, stores, and updates the calorific value conversion coefficient k based on the formula of calorific value conversion coefficient k = fuel addition amount / differential temperature integrated value / total inflow gas amount.

In step S260, the control means 25 sets the coefficient update flag = 1, ends step S200 (acquisition and update of calorific value conversion coefficient), and returns to the overall process.

In step S265, if the control means 25 determines that fuel is being added (Yes), the process proceeds to step S270, and if it is not determined that fuel is being added (No), step S200 (heat generation). (Acquisition and update of quantity conversion coefficient) is completed, and the process returns to the overall processing.

In step S270, the control means 25 controls the fuel addition valve 54, ends the addition of fuel to the exhaust passage 12, ends step S200 (acquisition and update of calorific value conversion coefficient), and proceeds to the overall processing. return.

● [Explanation of the overall configuration and operation of the exhaust gas purification device 20A of the second embodiment (FIGS. 3 and 4)]
A second embodiment for carrying out the present invention will be described with reference to FIGS. 3 and 4. FIG. 3 is a block diagram illustrating an overall configuration of the internal combustion engine 10 to which the exhaust gas purification device 20A of the second embodiment is applied. FIG. 4 is a flowchart illustrating a control process in the exhaust gas purification device 20A of the second embodiment.

● [Explanation of the overall configuration of the exhaust gas purification device 20A (Fig. 3)]
The overall configuration of the internal combustion engine 10 to which the exhaust gas purification device 20A of the present invention is applied will be described with reference to FIG. The exhaust gas purification device 20A differs from the exhaust gas purification device 20 of the first embodiment in that it has an injector 56 instead of the fuel addition valve 54. Therefore, a detailed description of the overall configuration of the exhaust gas purification device 20A will be omitted.

● [Explanation of operation in exhaust gas purification device 20A (Fig. 4)]
The control processing procedure of the control means 25 (see FIG. 3) in the exhaust gas purification device 20A (see FIG. 3) will be described with reference to the flowchart of FIG. The control processing procedure of the control means 25 in the second embodiment is different from the control processing procedure in the first embodiment in step S200A (heat generation) instead of step S200 (acquisition and update of calorific value conversion coefficient). It differs in that it has (acquisition and update of quantity conversion coefficient). When the control means 25 is activated, the control means 25 executes the entire process at predetermined time intervals (for example, several [ms] intervals). Hereinafter, each step will be described in detail. In addition, different processes are indicated by thick lines for clarity.

● [Explanation of acquisition and update of calorific value conversion coefficient (step S200A)]
As shown in FIG. 4, in the overall processing, the control means 25 performs the processing of step S200A instead of step S200. Hereinafter, the differences from step S200 in step S200A will be described in detail.

In step S215A, the control means 25 controls the injector 56 (see FIG. 3) and post-injects it into the cylinder of the internal combustion engine 10 (see FIG. 3) to inject fuel (fuel for coefficient calculation) into the oxidation catalyst 41 (see FIG. 3). 3), and the process proceeds to step S225.

In step S250A, the control means 25 controls the injector 56 to finish adding fuel to the cylinder of the internal combustion engine 10, and proceeds to step S255.

As shown in FIG. 3, the fuel added by the post injection in the injector 56 reaches the oxidation catalyst 41 via the exhaust passage 12. Therefore, in order to more accurately obtain the inflow gas amount, the inflow gas temperature, and the outflow gas temperature in the oxidation catalyst 41, the inflow gas amount, the inflow gas temperature, and the outflow gas after the added fuel reaches the oxidation catalyst 41. Get the temperature. Specifically, the fuel arrival time, which is the time for the fuel added by the post-injection in the injector 56 to reach the oxidation catalyst 41, is measured in advance and stored in the control means 25. In step S255, the control means 25 does not integrate the inflow gas amount, the inflow gas temperature, and the outflow gas temperature from the start of the post injection to the fuel arrival time, and starts the integration after the fuel arrival time elapses, and the total inflow gas amount. , Obtain the differential temperature integrated value. Further, the control means 25 may start the integration and obtain the total inflow gas amount and the differential temperature integrated value when the difference between the outflow gas temperature and the inflow gas temperature becomes equal to or more than a predetermined value stored in advance. good.
● [Effect of the present application]

As described above, the exhaust purification device shall perform the filter regeneration treatment in the DPF with the optimum fuel regardless of the degree of deterioration of the oxidation catalyst and the fuel properties, improve the fuel efficiency, and maintain the performance of the DPF. Can be done.

The exhaust gas purification device of the present invention is not limited to the configuration, structure, shape, etc. described in the present embodiment, and various changes, additions, and deletions can be made without changing the gist of the present invention.

10 Internal combustion engine 11 Intake passage 12 Exhaust passage 20 Exhaust purification device 20A Exhaust purification device 22 Fuel tank 24 Fuel meter 25 Control means 31 Inflow gas amount acquisition means 33 Accelerator opening detection means 34 Rotation detection means 41 Oxidation catalyst 42 Filter 50 Inflow gas Temperature acquisition means 52 Outflow gas temperature acquisition means 54 Fuel addition valve 56 Injector

Claims (6)

A filter that collects particulate matter contained in the exhaust gas discharged from the internal combustion engine,
It has an oxidation catalyst arranged on the upstream side of the filter.
In the exhaust purification device that purifies the exhaust gas,
An inflow gas amount acquisition means for acquiring the inflow gas amount, which is the inflow amount of the gas flowing into the oxidation catalyst,
An inflow gas temperature acquisition means for acquiring the inflow gas temperature, which is the temperature of the gas flowing into the oxidation catalyst,
An outflow gas temperature acquisition means for acquiring an outflow gas temperature, which is the temperature of the gas outflow from the oxidation catalyst,
With control means,
The control means
When it is determined that a predetermined amount or more of particulate matter has been collected in the filter, a filter regeneration treatment is performed in which fuel for filter regeneration is added to the oxidation catalyst to burn and incinerate the particulate matter in the filter.
Prior to the filter regeneration treatment, a calorific value conversion coefficient indicating the relationship between the temperature rise temperature of the exhaust gas and the amount of the filter regeneration fuel added to the oxidation catalyst was obtained.
When calculating the calorific value conversion coefficient,
The amount of fuel added and
The amount of the inflow gas, the temperature of the inflow gas, and the temperature of the outflow gas while the fuel of the fuel addition amount is being added to the oxidation catalyst.
Calculate the calorific value conversion coefficient based on
The filter regeneration fuel to be added to the oxidation catalyst during the filter regeneration treatment is adjusted based on the calorific value conversion coefficient.
Exhaust purification device. The exhaust gas purification device according to claim 1.
The control means
The calorific value conversion coefficient is obtained during idling operation or deceleration operation of the internal combustion engine.
Exhaust purification device. The exhaust gas purification device according to claim 1 or 2.
The control means
After refueling the fuel in the internal combustion engine, the preset initial calorific value conversion coefficient is referred to as the calorific value conversion coefficient until the calorific value conversion coefficient is obtained and updated only once after refueling based on the fuel after refueling. do,
Exhaust purification device. The exhaust gas purification device according to any one of claims 1 to 3.
The control means
When calculating the calorific value conversion coefficient,
The amount of fuel added and
The differential temperature integrated value obtained by integrating the difference between the outflow gas temperature and the inflow gas temperature while the fuel of the fuel addition amount is being added to the oxidation catalyst, and the inflow gas amount.
To obtain the calorific value conversion coefficient based on
Exhaust purification device. The exhaust gas purification device according to any one of claims 1 to 4.
The fuel for the oxidation catalyst is
It is added by a fuel addition valve arranged in the exhaust passage on the upstream side of the oxidation catalyst.
Or
Added by post-injection by an injector in the cylinder of the internal combustion engine.
Exhaust purification device. The exhaust gas purification device according to any one of claims 1 to 5.
When calculating the calorific value conversion coefficient
When the operating state of the internal combustion engine is a predetermined operating state, a predetermined fixed amount of fuel for calculating a coefficient to be added to the oxidation catalyst is consumed in the oxidation catalyst for a predetermined time. ,Added,
Exhaust purification device.

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